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PubMed1994

[Effects of ethyl all-cis-5,8,11,14,17-icosapentaenoate (EPA-E) on elasticity and endothelium-dependent relaxation of the aorta in high cholesterol diet-fed rabbits].

We studied the elasticity and endothelium-dependent relaxation (EDR) of the aorta in 1% cholesterol diet (HCD)-fed rabbits. Furthermore, the effects of ethyl all-cis-5,8,11,14, 17-icosapentaenoate (EPA-E) were examined in this model of atherosclerosis. After 12 weeks of feeding with HCD, the animals showed increase in plasma total cholesterol level, formation of atherosclerotic plaque, decrease in aortic elasticity and impairment of EDR to acetylcholine (ACh). The levels of aortic elasticity in HCD-fed rabbits administered orally with EPA-E (300 mg/kg for 12 weeks) were almost the same as those of rabbits fed a normal diet, although EPA-E showed no effects on the plasma total cholesterol level and formation of atherosclerotic plaque in HCD-fed rabbits. On EDR in response to ACh and cyclic GMP formation in the HCD-fed rabbit aorta, EPA-E improved the impairment of these parameters, but not significantly. Therefore, EPA-E had little effect on the endothelium in this model of atherosclerosis, although EPA-E improved the decrease in the aortic elasticity. Because the levels of aortic elasticity showed no significant correlation with the magnitude of EDR to ACh or the size of atherosclerotic plaque, the decrease of aortic elasticity in this model of atherosclerosis was thought to have little relation to the dysfunction of the endothelium.

Acetylcholine↗
PubMed2000

Scaling analysis of the concentration dependence on elasticity of agarose gel.

Since the critical exponent of the elastic modulus is related to the spatial dimension and the critical exponent of the correlation length, depending on the characteristics of elasticity, we experimentally evaluated both the elastic modulus of a sol-gel transition system and also the correlation length. We could determine the correlation length of agarose gel by the dynamic light scattering method; it was well described by the power law as a function of the deviation from the sol-gel transition point. Three scaling laws between the critical exponent of the correlation length (v) and that of the elastic shear modulus (t) were compared, and the critical exponent of the elastic modulus was described by the equation of de Gennes expression (t=1+v(d-2), where d is the spatial dimension). This result suggests that agarose fibers are stiff enough to show scalar elasticity.

Dose-Response Relationship, Drug↗
PubMed2025

Reverse transcription progression and genome length regulate HIV-1 core elasticity and disassembly.

The structural and mechanical properties of the HIV-1 core are critical for successful infection, balancing stability for early replication and controlled disassembly for genome release. Recent studies have highlighted the role of core elasticity in nuclear entry, yet the molecular determinants regulating this property remain poorly understood. Here, atomic force microscopy (AFM) was used to investigate the relationship between reverse transcription progression, genome length, core elasticity, and disassembly. The results demonstrate that reverse transcription induces a gradual loss of elasticity, rendering the core increasingly brittle as DNA synthesis progresses. Cores containing shorter genomes remained highly elastic, whereas those with longer genomes exhibited increased brittleness, structural damage, and a higher degree of disassembly, after 4 hours of reverse transcription. Additionally, cores from an RNase H-deficient HIV-1 mutant retained high elasticity. These findings provide insight into the interplay between genome synthesis, core integrity, and nuclear entry, supporting a model in which reverse transcription-generated mechanical stress facilitates uncoating. Furthermore, early-stage reverse transcription preserved core elasticity, suggesting a temporal window for successful nuclear import before structural destabilization compromises infectivity.

HIV-1↗
PubMed1991

Effects of elastic loading and exercise on pulmonary gas exchange in dogs.

We assessed the effects of negative intrathoracic pressure induced by inspiratory elastic loading on pulmonary, gas exchange with and without electrically induced hindlimb exercise in 8 normal, anesthetized dogs. Two elastic loads (EL) were used; one of 81 and one of 140 cmH2O/liter. These are equivalent to doubling and tripling the normal elastance of the dog's respiratory system, respectively. Elastic loading decreased ventilation and caused hypoxemia and hypercapnia, but it did not affect systemic arterial pressure or heart rate. During exercise, increase in ventilation was limited, whereas increase in cardiac output was not affected by elastic loading. Alveolar-arterial O2 tension difference (A-aDO2) was not changed significantly by exercise alone. However, elastic loading accompanied by exercise increased A-aDO2. Although comparable end-inspiratory pleural pressure was achieved with large EL (-29 +/- 2 cmH2O, mean +/- SE) and small EL with exercise (-30 +/- 2 cmH2O), the latter increased A-aDO2 whereas the former did not. Large negative intrapleural pressure combined with increased cardiac output may have caused transient interstitial edema.

Animals↗
PubMed2006

Elasticity analyses of size-based red and white abalone matrix models: management and conservation.

Prospective elasticity analyses have been used to aid in the management of fished species and the conservation of endangered species. Elasticities were examined for deterministic size-based matrix models of red abalone, Haliotis rufescens, and white abalone, H. sorenseni, to evaluate which size classes influenced population growth (lambda) the most. In the red abalone matrix, growth transitions were determined from a tag recapture study and grouped into nine size classes. In the white abalone matrix, abalone growth was determined from a laboratory study and grouped into five size classes. Survivorship was estimated from tag recapture data for red abalone using a Jolly-Seber model with size as a covariate and used for both red and white abalone. Reproduction estimates for both models used averages of the number of mature eggs produced by female red and white abalone in each size class from four-year reproduction studies. Population growth rate (lambda) was set to 1.0, and the first-year survival (larval survival through to the first size class) was estimated by iteration. Survival elasticities were higher than fecundity elasticities in both the red and white matrix models. The sizes classes with the greatest survival elasticities, and therefore the most influence on population growth in the model, were the sublegal red abalone (150-178 mm) and the largest white abalone size class (140-175 mm). For red abalone, the existing minimum legal size (178 mm) protects the size class the model suggests is critical to population growth. Implementation of education programs for novice divers coupled with renewed enforcement may serve to minimize incidental mortality of the critical size class. For white abalone, conservation efforts directed at restoring adults may have more of an impact on population growth than efforts focusing on juveniles. Our work is an example of how prospective elasticity analyses of size-structured matrix models can be used to quantitatively evaluate research priorities, fishery management strategies, and conservation options.

Animals↗
PubMed2006

Failure of elastic fiber homeostasis leads to pelvic floor disorders.

Pelvic floor disorders, a group of conditions affecting adult women, include pelvic organ prolapse and urinary incontinence. Vaginal childbirth and aging are risk factors, and weakening of the pelvic support structures is a major aspect of the pathology. However, the underlying molecular mechanism remains unknown. Female reproductive organs are rich in elastic fibers that turn over slowly in most adult tissues but undergo massive remodeling in the reproductive organs through pregnancy and birth. Here we show that a failure to maintain elastic fiber homeostasis in mice causes pelvic floor disorders. Lysyl oxidase-like-1 (LOXL1), a protein essential for the postnatal deposition of elastic fibers, was highly expressed and regulated in the reproductive tract of the mouse, and its expression was diminished during aging. LOXL1 deficiency caused an inability of reproductive tissues to replenish elastic fibers after parturition, leading to pelvic organ prolapse, weakening of the vaginal wall, paraurethral pathology, and lower urinary tract dysfunction. These data demonstrate the importance of elastic fibers for maintaining structural and functional integrity of the female pelvic floor. Our findings raise the possibility that a failure of elastic fiber homeostasis, either due to genetic predisposition or advancing age, could underlie the etiology of pelvic floor dysfunction in women.

Amino Acid Oxidoreductases↗
PubMed1980

Physiological features of the pressure-volume function of brain elasticity in man.

The intracranial pressure-volume relationship of brain elasticity was examined in 20 patients with suspected disorders of the cerebrospinal fluid (CSF) system. Elasticity measurements were made as the patients were studied with a servo-controlled lumbar infusion technique to measure CSF absorptive capacity. The data were evaluated to determine the relationship between intracranial pressure (ICP) and volume, and between ICP variability and the level of ICP. The results confirm the exponential nature of the pressure-volume elasticity function in patients who are not critically ill. Eight of the 20 patients were shown to have normal CSF absorptive capacities, and there was no difference between their elasticity measurements and those of patients with absorptive defects. In addition, ICP variability was shown to be linearly related to the actual level of ICP. The physiological features of the pressure-volume elasticity function are reviewed. Based on these considerations, the clinical value and significance of elasticity measurements is questioned.

Adolescent↗
PubMed2005

[Effect of psychological pressure on muscle elasticity and the function of the autonomic nervous system].

The purpose of this study was to clarify the following: (1) effect on the elasticity of the musculus trapezius caused by psychological load, and (2) relationship between psychological load, muscle elasticity, and the autonomic nervous system (ANS) by frequency analysis of heart rate variability. The experiment was conducted on a group of 30 healthy volunteers, consisting of 16 males and 14 females with an average age of 31.2 years old. We investigated and compared the changes in muscle elasticity and ANS in the case of control (resting), phonating and mental calculation as psychological load. Psychological status and stress response were measured by using State-Trate Anxiety Inventory (STAI), Stress Checklist (SCL), and Stress Tolerance Checklist (STCL). As a result, the subjects experienced effective acute emotional stress during mental calculation, and muscle elasticity increased significantly. Heart rate (HR), low frequency (LF) component, and LF/HF increased significantly during mental calculations. The high frequency (HF) component tended to decrease during mental calculations. The rate of elevation of muscle elasticity and HR (difference between at rest and when calculating) was significantly related to STAI and STCL. STCL was significantly related to state of anxiety. The results of this study suggest that anxiety and stress tolerance affect muscle elasticity.

Adult↗
PubMed1999

Skin elastic fibers in Williams syndrome.

The elastin gene is consistently deleted in Williams syndrome and as this protein represents the major component of the elastic fibers of the dermis, we sought to investigate skin elastic fibers in Williams syndrome as a key to unraveling extracellular matrix disorganization in this condition. Both morphometric parameters analyzed by using automated image analysis and immunofluorescence labeling with monoclonal antibodies against elastin and fibrillin 1 showed a disorganized pre-elastic (oxytalan and elaunin) and mature elastic fibers in the dermis of 10 Williams syndrome patients compared with five healthy children and one patient with isolated supravalvular aortic stenosis. Skin biopsies in Williams syndrome patients provide a simple mean to elucidate extracellular matrix anomalies. Hopefully, this method could give clues to the understanding of the elastic network anomalies in this condition and even to the consequences of these latter on elasticity and resilience of other tissues such as the arterial tree.

Adolescent↗
PubMed2001

[Changes in aortic elasticity in aged patients with essential arterial hypertension].

Aortic elasticity was studied in aged patients with mild and moderate arterial hypertension using magnetic resonance imaging. The analysis of changes in cross section area (CSA) of the ascending aorta in systole has shown that in some patients maximal CSA occurs in different systolic phases while in the other patients CSA remains unchanged. Calculation with the elasticity rate proved that patients with maximal aortic diameter at the beginning of the systole have maximal aortic elasticity while those with minimal changes in aortic diameter in the course of the systole have minimal elasticity. Thus, in aged patients with mild and moderate essential hypertension aortic wall loses its elasticity to different extent. Further studies will specify clinical and pathogenetic implications of reduced aortic elasticity in arterial hypertension.

Aged↗
PubMed2001

[Ultrasonic measurement of the elastic properties of goat condyles].

OBJECTIVE: The purpose of this experiment is to investigate the elastic properties of goat mandibular condyles and to provide basic constants for biomechanical study of temporomandibular joint. METHODS: A fresh goat mandible was adopted and the standard condyle specimen of 4 mm x 6 mm x 10 mm was obtained from it. The structure density of the condyle was determined according to Archimede's principle. The transmitting velocities of ultrasonic wave in different directions of goat condyles were measured by using the ultrasonic system, which was composed of a transmitting transducer of 1.25 MHz, a receiving transducer of 2.5 MHz, an ultrasonic analyzer (5052UA) and a digital storage oscilloscope (HP54601A). The elastic coefficients and technical constants could be calculated by elastic equations. RESULTS: The structural density of the sample and the wave velocities in different directions of the condyle were both obtained by direct measurement. And then, nine elastic coefficients and all of the technical constants of orthotropic condyles were calculated. CONCLUSION: 1. It is practicable to measure elastic properties of the condyle by using ultrasonic technique. 2. Goat condyles of the mandible are a type of anisotropic and linearly elastic material. 3. The direction perpendicular to the transverse ridge of the goat condyle has the highest Young's modulus. As to shear modulus, the direction along the transverse ridge shows the highest value.

Animals↗
PubMed2004

Nonlinear elasticity imaging: theory and phantom study.

In tissue the Young's modulus cannot be assumed constant over a wide deformation range. For example, direct mechanical measurements on human prostate show up to a threefold increase in Young's modulus over a 10% deformation. In conventional elasticity imaging, these effects produce strain-dependent elastic contrast. Ignoring these effects generally leads to suboptimal contrast (stiffer tissues at lower strain are contrasted against softer tissues at higher strain), but measuring the nonlinear behavior results in enhanced tissue differentiation. To demonstrate the methods extracting nonlinear elastic properties, both simulations and measurements were performed on an agar-gelatin phantom. Multiple frames of phase-sensitive ultrasound data are acquired as the phantom is deformed by 12%. All interframe displacement data are brought back to the geometry of the first frame to form a three-dimensional (3-D) data set (depth, lateral, and preload dimensions). Data are fit to a 3-D second order polynomial model for each pixel that adjusts for deformation irregularities. For the phantom geometry and elastic properties considered in this paper, reconstructed frame-to-frame strain images using this model result in improved contrast to noise ratios (CNR) at all preload levels, without any sacrifice in spatial resolution. From the same model, strain hardening at all preload levels can be extracted. This is an independent contrast mechanism. Its maximum CNR occurs at 5.13% preload, and it is a 54% improvement over the best case (preload 10.6%) CNR for frame-to-frame strain reconstruction. Actual phantom measurements confirm the essential features of the simulation. Results show that modeling of the nonlinear elastic behavior has the potential to both increase detectability in elasticity imaging and provide a new independent mechanism for tissue differentiation.

Algorithms↗
PubMed2004

The elastic properties of cancerous skin: Poisson's ratio and Young's modulus.

BACKGROUND: The physical properties of cancerous skin tissue have rarely been measured in either fresh or frozen skin specimens. Of interest are the elastic properties associated with the skin's ability to deform, i.e., to stretch and compress. Two constants--Young's modulus and Poisson's ratio--represent the basic elastic behavior pattern of any elastic material, including skin. The former relates the applied stress on a specimen to its deformation via Hooke's law, while the latter is the ratio between the axial and lateral strains. OBJECTIVES: To investigate the elastic properties of cancerous skin tissue. For this purpose 23 consecutive cancerous tissue specimens prepared during Mohs micrographic surgery were analyzed. METHODS: From these specimens we calculated the change in radial length (defined as the radial strain) and the change in tissue thickness (defined as axial strain). RESULTS: Based on the above two strains we determined a Poisson ratio of 0.43 +/- 0.12 and an average Young modulus of 52 KPa. CONCLUSIONS: Defining the elastic properties of cancerous skin may become the first step in turning elasticity into a clinical tool. Correlating these constants with the histopathologic features of a cancerous tissue can contribute an additional non-invasive, in vivo and in vitro diagnostic tool.

Cryopreservation↗
PubMed2005

[Impaired endothelium-dependent vasodilation and arterial elasticity in patients with coronary artery disease].

OBJECTIVE: To investigate the change in endothelium-dependent vasodilation and arterial elasticity and the association between them in patients with coronary artery disease (CAD). METHODS: Thirty patients with CAD and thirty control subjects were recruited for this study. Flow-mediated dilation (FMD) in the brachial artery was evaluated by ultrasound Doppler flow method. They also underwent a non-invasive assessment of C(1) large artery and C(2) small artery indices by using pulse wave analysis. RESULTS: FMD was significantly reduced in CAD group compared with that in control group [(5.17 +/- 2.13)% vs (11.1 +/- 4.36)%, P < 0.05], C(1) large artery elasticity index was similar between the two groups [(11.59 +/- 4.56) ml/mm Hg x 10 vs (12.11 +/- 3.82) ml/mm Hg x 10, P > 0.05]. However, C(2) small artery elasticity index was significantly reduced in CAD group compared with that in control group [(4.20 +/- 1.80) ml/mm Hg x 100 vs (6.26 +/- 2.36) ml/mm Hg x 100, P < 0.05]. There was a positive association between reduced C(2) small artery elasticity index and impaired FMD (r = 0.53, P < 0.05). CONCLUSIONS: There were impaired endothelium-dependent vasodilation and reduced C(2) small artery elasticity index in the patients with CAD, which were closely correlated with each other. The present study suggested that the measurement of C(2) small artery elasticity might be used as a novel index for the determination of endothelial function.

Aged↗
PubMedDate not supplied

Influence of centrifugal blood pumps on the elasticity of erythrocytes.

The influence of centrifugal blood pumps on the elasticity of erythrocytes was tested in an in vitro set-up. Fresh bovine blood was pumped by vaneless and impeller blood pumps with low and high hemolytic potential (1L priming volume, flow 5 L/min versus 150 mmHg, pumping time 6 hours). The elasticity of the red blood cells was measured by laser diffraction. Starting with an elasticity of 238 +/- 39, the overall change during 6 hours was 12 +/- 38 compared to a change of the control value of -13 +/- -58. Even a pump with very high hemolytic potential (Hemolysis index 21.9) did not cause relevant changes of elasticity. It is concluded that 1) elasticity is not a useful parameter to use in the evaluation of centrifugal pumps, and 2) the mechanical trauma caused by centrifugal pumps produces no relevant permanent alteration of the elastic properties of red blood cells, at least under in-vitro conditions.

Animals↗
PubMed1991

Elastic fiber components and protease inhibitors in pinguecula.

The nature of the abnormal elastotic materials seen in pingueculae and their insensitivity to elastase are poorly understood. The authors investigated their composition by immunoelectron microscopy using antibodies to elastic fiber components, serum and tissue components known to be associated with elastosis in other sites. The abnormal elastic fibers showed labeling for elastin, microfibrillar protein, and amyloid P where these components never co-localize normally, indicating the fibers are not simply immature but aberrant in organization. There was mild positivity for the serum protease inhibitor alpha-1 antitrypsin at the edges of the abnormal elastic tissue and marked positivity for lysozyme. The more superficial region of pingueculae had similar elastic constituents but no fiber formation and a paucity of elastic microfibrils. The subepithelial dense concretions showed strong staining for lysozyme, the first component to be identified in these aggregates. Amyloid P and lysozyme are characteristic components of dermal elastosis, postulated to have an inhibitory effect on elastolytic processes, indirectly affecting the control of elastogenesis. The greater prominence of nonfiber-forming aggregates in pingueculae may be related to their marked deficiency of elastic microfibrils compared with dermal elastoses. This difference speaks for more severe actinic cellular damage in the poorly protected conjunctival tissue.

Aged↗
PubMed1989

A subepithelial elastic lamina in the palpebral conjunctiva of monkeys.

Eyelids from ten cynomolgus monkeys were sectioned in a variety of orientations and the conjunctival layer examined by light and electron microscopy. An elastic lamina composed of a mesh of mature elastic fibres was present in the palpebral conjunctival stroma adjacent to the epithelium covering the area of the tarsal plate and extending to the lid margin. Mesh fibres orientated at or close to right angles to the lid margin were thicker and denser than the transverse and oblique fibres linking them. The elastic lamina was most substantial in the marginal conjunctiva bridging the interval between the tarsal plate and the mucocutaneous junction where it terminated abruptly. In this position the area occupied by the elastic mesh exceeded that of the mesh spaces. Dense collagen bundles enclosed the lamina, infiltrating the mesh spaces and attaching the lamina firmly to the tarsal plate. In the marginal zone thick elastic fibres branched forward from the lamina in a brush-like fashion penetrating the relatively soft marginal eyelid tissue obliquely between tarsal gland ducts, while other finer, more numerous fibrils passed backwards attaching the lamina to the basement membrane of the epithelium. The organisation of the elastic lamina suggests that the tension generated would act to pull the lid margins towards the surface of the eye. Production of a regular thin tear film during lid retraction following a blink is facilitated by this action.

Animals↗
PubMed1989

Elastic tissue changes in generalized granuloma annulare.

The histological picture in granuloma annulare (GA) is well defined. The types of infiltrate and the changes in collagen and elastic tissue have been repeatedly described. This is a preliminary study focused on the elastic tissue changes in lesions of generalized GA. Biopsies from four patients were studied. Specimens of involved and uninvolved skin from both exposed and unexposed parts of the body were compared. Changes of actinic elastosis in the papillary dermis in each patient in different stages were observed only in the exposed skin. The typical GA infiltrate was located beneath, in the upper mid-dermis. In the zone of the infiltrate in all specimens--exposed and unexposed--with no regard to the severity of actinic elastotic changes, absence or a marked reduction of elastic material was noted with engulfment of elastic remnants in giant cells. Giant cells with phagocytosis of elastotic material were mostly located on the periphery of the granuloma in the upper as well as in the deeper portion, where elastic fibers were still present. This might support the suggestion that degenerating elastic fibers promote the granulomatous reaction that leads to the formation of granuloma annulare.

Aged↗